Telephone system



- Jialy 29 1924.

H. D. CURRIER ET AL TELEPHONE SYSTEM -Or i Sheets-Sheet 1 H. D. CURRIER ET AL TELEPHONE SYS TEM MTEZYYZYZUPPZPP July 29. 1924 H. D. CURRIER ET \AL/ TELEPHONE SYSTEM o i inal Filed Feb. 24.

5 SheetsSheet 5 E 1/527 0P5; 4 1772172772] E zzz'rz'er' M 29, 1924. H y g 15%,095

' H. D. CURRIER. ET AL TELEPHONE SYSTEM Original Filed Feb. 24, 1919 5 SheetsShee Hzfaml? E 7.21"! 2'91" .5901"; 5135572722 .357 fiflbrney.

Jul 29, 1924. 1,503,095

' H. D. CURRIER ET- AL TELEPHONE SYSTEM 5 Sheets-Sheet S Original Filed Feb. 24,

.FeargefiEaTUzz 5 HUM-27E HIRAM D. CURBIEB, OF CHICAGO, AND GEORGE E. EATON, OF OAK PARK, ILLINOIS, ASSIGNORS '10 KELLOGG SWITCEBOABD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYST.

Application file'd February 24, 1919, Serial No. 278,745. Renewed September 17, 1923.

To all whom it may concern:

Be it known that we, HIRAM D. CURRIER and GEORGE R. EATON, citizens of the United vStates of America, residing in Chicago, county of Cook, and Oak Park, county of Cook, respectively, in the State of Illinois, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

Our invention relates to telephone systems in which link or cord circuits are employed for interconnecting telephone lines, and has to do more particularly with that type of telephone systems employing manual switchboards.

At present there are a great many switchboards in use which have reached their maximum capacity in the number of lines that can be handled and in the number of calls that can be handled, and it is to this type of boards, aswell as to new installations, that 'our invention particularly relates. It now becomes necessary to increase the capacity of these boards and it is impossible to do so, owing to the fact that the present multiple of the switchboard has been filled up to the limit, and in a great many cases new positions or sections can not be added owing to the fact that the switchboard entirely fills the room or ofiice in which it is situated. We are thus confronted with these conditions and must find some wa to rehabilitate a board of thischaracter or the reason that the board may be practically new and in first-class working condition, making it undesirable to do away with the same and install an entirely new board.

An object of our invention is to increase the capacity of the so-called multiple line lamp boards in which the multiple acks are not only used for answering purposes but are also used for calling purposes. In a board of this type the answering jacks and lamps which are individual to the subscribers lines are multipled, several times, through the board and these jacks are not only used for answering purposes but are alsoused for calling purposes. In view of the fact that the jacks and lamps are multipled several times through the board, so that each operator can reach-a jack of every line, the number of lines which may be installed in any one board is naturally limited to a certain number. It is a feature of our invention to arrange a system whereby the multiple answering jacks and lamps are not individual to the lines, but are common to the lines thereb decreasing the total number of multiple' answering 'acks and lamps required for a definite num er of subscribers, and providing enough space whereby the usual multiple jacks, which require a great deal less space than answering jacks, may be multipled through the dilferent sections of the board. We provide a certain number of trunks terminating in multiple jacks and lam s for each group of subscribers. The num er of trunks rovided, which are common to the subscribers lines, depends-upon the amount of traflic out of any one group of lines. By this method of distribution and in conjunction with the socalled feature cord clrcuit, we are able to greatly increase the efficiency of operation, as well as to greatly reduce the cost of operation.

Another object of our invention is to materially incream the capacity of the present existing boards as well as to increase the efliciency, decrease the cost of operation, etc. of the board. In explaining our invention, we will refer to the existing type of board as it nowappears, and as it will appear after we have rehabilitated the same. For

example, we will consider the standard type i of switchboard which has a capacity of 9600 lines, and assume that it has reached its capacity. A switchboard of this type is generally provided with eight panel sections and each panel is provided with 80 answering jacks and 80 line lamps, thereby making a total of 640 answering jacks and answering lamps per section. Each section of the board, of course, contains 9600 multiple jacks for the 9600 subscriber's lines, and further assuming that this switchboard is provided with the ordinary well-known cord circuit that was generally installed up until a few years ago which did not have the present automatic features contained in the cord circuits of to-day; In such a board each of the operators, at the three positions to a section, can handle an average of 240 calls per busy hour, thus making an average total of 720 calls per busy hour for any one section. That is a calling rate of 1.12 calls per line per busy hour of the lines in a section. It is necessary to provide this type of board with 120 panels since each panel contains 80 answering jacks and 80 divided into 9600, the number of lines appearing in this board, gives 120 panels. There being 8 panels per section, it requires a section board for the 9600 lines. Now, in view of the fact that the first operator and the last operator on' the board would not'be in a position to reach the entire 9600 multiples with only a 15 section board, it is necessary to provide 16 sections to'take care of the 9600 lines, and an operator is not provided at the first position or at the last two positions on'the 16 section board. To handle the traflic on this board at the busy hour, it would require operators, that is, there would be 3 operators at each section, neces sitating 45 operators at the 45 equipped positions. With the calling rate of 1.12 calls per line per busy hour, the total number of calls per busy hour from the 9600 lines would be 10,752 calls. So much for the old 7 type of board which is not equipped with any of the present day automatic telephone 1 features.

It is a feature of our invention to re habilitate a board of this type or of any other standard type, and for the purpose of illustration and description, we have assumed a board of the above-described type. We will now describe our method of rehabilitating such a board. Now, by providing the cord circuits at the operators positions with the well-known feature type of cord circuit including automatic listening, automatic disconnection, automatic ringing, automatic recall, call distribution, etc. it has been found that the average operator will be able to easily handle on the average 400 calls per busy hour instead of 240, as was the case with the old type of switchboard. Taking the total number of calls per busy hour, which we mentioned above as 10,752. we find that with .the operator handling e calls an hour it will be necessary to provide approximately 27 operators to handle the said number of calls during the busy hour. It was necessary with the old board, as shown above, to place operators at 45 of the positions to handle the same number of calls, and now it is only necessary to place operators at 27 positions or at 9 sections of the board. Of course. we will have to provide an extra section as we did above in. view of the fact that the operators can not be placed at the end positions of the board, thereby necessitating a board of 10 sections for the 27 operators to handle the 10,752 calls. By this method, it is at once apparent that we are able to handle the same number of calls with a board consisting of 10 sections instead of 16 sections. Now, in order to increase the capacity of the board we decrease the number of answering acks and line lamps from 9600, as was previously necessary when one answering jack was provided for each subscribers line, to about 3500 or 3600 answering jacks, by the following method. e terminate the subscribers lines in the banks of finder switches; each group of 50 subscribers lines is multiply connected through the banks of 6 finder switches, making a total of 12 finder switches for 100 lines, or about 1152 finder switches for the 9600 lines. We then terminate the finder switches at their one end in multiple answering jacks and multiple line lamps, the answering jacks, being multipled through different positions, thereby distributing the calls and permitting the operators to work at their maximum efficiency theentire time that calls are appearing upon the board, because the calls appear before a number of operators and can be answered by any one of the operators before which it appears.

iVe have arbitrarily divided this 10 position board into 4 different parts or zones having 2400 lineseach, that is, 1/4 of the 9600 lines appear in each zone or part. We have multipled the answering jacks associated with the finder switches 3 different viding the 72 panels into 4: equal zones or sections, we have 18 panels to each zone or division of the board. For the 24:00 lines in any one zone of the board we provide 21- times 12 switches or 288 switches, and assuming that each switch appears in 3 multiple jacks, it will require 3 times 288 or 861 answering jacks; for the purpose of cal culation, we will say 900 answering jacks per zone of the switchboard. With 18 panels per zone, we have 1/18 part of 900 answering jacks or 50 answering jacks per panel. lVith this arrangement it is at once apparent that when a subscriber calls, an idle finder switch will connect his line to the associated answering jacks that appear 3 times in the 18 panels, thereby giving a plurality of operators an opportunity to seize the calling line. It is also at once apparent that at the idle hours one operator may be placed in each zone of the board and be able to reach and handle all of the calls that come in on the 6 panels in front of her without moving. By using only 50 answering jacks per panel, it is at once apparent that we have a saving of the space previously required for 30 answering jacks and line lamps per panel, that is, we have a saving of 8 times the space required for 30 answering jacks and line lamps per section of the switchboard ,or the saving of the space previously required for 240 jacks and lamps. In the space required for this number of answering jacks and answering lamps 1120 lot) . ficiency with an increased neoaoee c multiple jacks may be substituted, increasing the capacity of the board from 9600 to 10,720 lines. This, of course, is possible by being able to drop the multiple jacks down in the space that was saved by the decrease in number of answering jacks, and providing 1120 new multiple jacks in its place. With 1120 new subscribers lines we will have to add extra positions to take care of these lines.

From the foregoing it will be seen that a feature of our invention resides in the means used for materially increasing the capacity or number of lines that may appear upon a given size standard switchboard.

A further featureof our invention is the provision of means for increasing the efand the number of calls that an operator may handle per hour.

A still further feature of our invention is the means provided for terminating the finder switches in multiple jacks and lamps on the switchboard, thereby distributing the calls to the operators.

And still a further feature of our invention is the provision of a simplified automatic switch which is not provided with step-by-step mechanism and which is adapted to select on either a forward or on a backward movement.

These and other features will be more particularly pointed out in the ensuing specification and in the appended claims.

Referring to the accompanying drawings,

' Figure 1 shows a face view of a section of switchboard arranged with the old method of an answering jack and lamp per line, and with a capacity of 9600 multiple jacks;

Figure 2 shows a face view of a section of our improved switchboard provided with multiple answering jacks and line lamps which terminate in finder switches, and

from 9600 to.10,720, multiple jacks;

Figure 3 shows a face view of the old switchboard with the 16 sections;

Figure 4 shows our improved switchboard requiring only 10 sections, and with an increased capacity to 10,720 multiple jacks;

Figure 5 shows a top view of the finder switch of our invention;

Figure 6 shows a side view of the finder switch;

Figure 7, comprising parts 1 and-2, shows the complete circuit arrangement of a connection between a calling subscriber A and a called subscriber C, using our improved circuit arrangement.

Referring now to Figure 1 which shows a section of an ordinary switchboard of 9600 line capacity, the board comprises 8 panels X and is provided with 3 operators positions Y, each of which positions is prolamps,

capacity of multiple jacks- 9600 line capacity and vided with the necessary operators apparatus including 15 or 17 double-end operators cord circuits, keys, etc. At Z is shown the individual answering jacks and as before mentioned, there being 80 answering jacks and line lamps per panel or a total of 640 answering jacks and lamps per section. At U is shown the 9600 multiple jacks, there being one multiple jackfor each line in each section, each panel including 1200 multiple jacks, that is, 9600 multiple jacks for the 8 panels.

Referring now to Figure 2, we here show the same section of switchboard as shown in Figure 1, but afterit has been rehabilitated. This section also comprises 8 panels X and 3 operators positions Y. Each-panel X is provided with 50 answeringjacks Z which are multipled 3 timesthrough the 18 panels which comprises one zone of the switchboard. Each jack will appear in every sixth panel in the 18 panels. I shown 1340 multiple jacks U there being 10,720 multiple jacks U in each section.

Figure 3 shows a face' view of the standard 9600- line capacity board being provided positions Y, notnecessarily being equipped but so arranged that the opwith 16 sections V and with 48 positions Y, Y and Y erators at positions Y and Y can reach the entire mutiple of 9600.

In Figure 4 we show thesame board rehabilitated and providedwith' our new circuit arrangements. The board shown in Figure 4 is provided with 10 sections V and with 30 positions Y; only 27 of the positions. Y" being necessary, the endpositions I Y and Y onl being necessary for the reason mentioned a ove.

From the foregoing the great saving in In each panel X is the number of positions, equipment, operating expense, increased service and increased capacity that our invention permits of is at once apparent.

eferring now particularly to the switch structure as shown in Figures 5 and 6, it comprises a base plate 40 which supports a pair of rotary magnets RM and a mounting plate 41 which supports a frame member 42 that carries the bank contacts. The rotary magnets RM are fastened to the base plate 40 by means of screws extending up through the said base plate into the extended ends of the cores. Attached to the opposite end of the cores of the rotary magnets are a pair of soft iron pole-pieces 43, which extend inwardly and are provided with circular faces between which is mounted the rortary armature 44. Mounted immediately above and resting on the pole-pieces 43 is the mounting plate 41, which is of insulating material. The bank carrying frame 42, the mountin plate 4.1 and a bridge member 45 are all helc l in position by means of screws 46 that pass through these members andthrough collars 47 and have screw-threaded engagement with the cores of the rotary magnets RM. The bank carrying member 42 supports at itsfree end a semi-circular bank of contacts 48"including fifty-one sets of four contacts each, all of which contacts are suitably in- 3 and its other end attached to the base plate 40. Secured to the shaft 49 is the armature 44 which normally rests at an angle to the bridge member 45 and is adapted, when the rotary magnets R-M are energized, to ro- "tate about its axis until it is substantially parallel to the said bridge member 45. Se-

cured to the base plate 40 is an angular supporting plate 52 which carries. the governing mechanism for regulating the speed of operation of the rotary armature 44 and shaftof the switch.

'Attached to the shaft 49 is a gear wheel 53 which is adapted to be rotated therewith and to. engage a pinion 54 suitably and rotatably supported by the angular mounting plate 52. Attached to the shaft 55 which carries the pinion 54 is a second gear wheel 56 adapted to mesh with a pinion 57 carried by a shaft rotatably supported by the angular plate 52. Attached to the shaft which carries the pinion 57 is a rotary governing device, which is adapted, as above mentioned, to control the speed of operation of the switch. Therotary governing device is of a well-known type and comprises a pair of weighted members 58 that are'adapted 'to engage a circular drum 59 when the weightedmember's are rotated above a predetermined speed. A spring 60 tends to hold the weighted members in their normal positions. For a more complete understanding of the structure and operation of said governing means, reference'may be had to Patent 1,262,352, issued to W.

Kaisling April 9, 1918.

From the manner in which the governing device is connected to the shaft 49, it is at once apparent that said governing device is adapted to control, and regulate the speed of operation of the shaft 49 in both its forward and its retrograde rotary movements. Secured to the shaft 49 is a wiper carrying arm 61 and attached to the free extremity of the arm 61 arethecontact wipers 2, 3, 4 and 5. These wipers are, of course, suitably insulated from each other and from the arm 1 61.v Attached to the opposite end of the arm 61 is a soft iron holding member 62. This member is rivetally' attached to a spring 63 which in turn is rivetally attached xcarries a buffer-66 which engages the offnormal contacts ON when the arm61 is in its normal position,'and holds them'in their normal position.

Mounted immediately below the plate 41 is the holding magnet HM, which is provided with a core 67 and a heel iron 68. Attached to the free extremity of the core of the magnet HM is a soft iron strip 69, that in turn is attached to the mounting plate 41 by means of screws 70. Likewise attached to the heel piece 68 of the holding magnet HM is a soft iron strip 71 which is in turn attached to the plate 41 by means of screws 72. When the holding magnet HM is energized, the soft iron piece 62 carried by the arm 61 is adapted to be attracted by the strips 69 and 71 and frictionally engage the plate ;75 which is mounted between the. insulating plate 41 and the soft iron pieces '69 and 71 thereby holding the wiper shaft 161 and wipers in their advanced selected position. When the holding magnet HM is de-energized, the spring 63 removes th soft iron piece 62 from frictional engagement with the plate 75, thereby per mitting the wiper shaft and wipers to return to normal under the influence of the spring 50', retarded by the governing mech its retrograde movement by means of a frictional governor, and which device is provided with a holding magnet that is adapted to maintainthe switch shaft and wipers in their selected position by means of a frictional engaging member.

It may be well to mention at this point, that owing to the fact, in our system, that a finder switch is freed immediately upon the hanging u of the receiver at the calling substation and the immediate energization of the link disconnect relay LD of the cord circuit, the number of finder switches required to handle the trafiic may be greatly decreased. This is, by releasing thefinder switch for further use, the moment that the calling subscriber signals for disconnect, the time that the finder switch is held for use is greatly decreased over what it would be if it was necessary to wait for the operator to release the same. This feature of our invention is of' particular advantage in a. multiple line lamp system in which the line lamps are common to a plurality of sub nectedby the line limbs L to a scribers and it is desirable not to hold the common trunks longer than it isabsolutely necessary to. y

Our invention, of course, is applicable to new installations and is particularly applicable to call distribution systems and permits increasing the number of lines that may be conveniently handled in such a system on any one board by not making the multiple jacks and lamps individual to a subscribers line, but by making them common to a plurality of subscribers lines. It is to be understood one of the main features of our invention is th use of common trunks terminating in multiple answering jacks and lamps, in connection with a feature cord circuit having instantaneous disconnection.

Referring now in general to the preferred embodiment of our invention as illustrated in Figure 7, which comprises parts 1 and 2, it shows a calling substation A of the wellknown Kellogg common battery type concommon battery line circuit M which includes a line relay LR, a cut-0H relay CO, multiple jacks J and multiple bank contacts 0, P, Q, and R, ea'ch subscribers line appearing in the banks of 6' different finder switches. We have found under ordinary trunking conditions that 6. finder switches are sufficient to handle the trafiic or calls from a group of 50. lines. Of course,

we can increase the capacity of our finder switches to 100 or any I other number of lines desired,. and provide the switchboard, that is, associated with each finder switch appear in.

' the group of subscribers which isassociatedas many finder switches per group of lines as we find necessary and desirable to take care of the traiiic.

The finder switch FS terminates at its one end in multiple jacks MJ and in multiple line lamps S', a jack MJ and lamp S appearing in every seventh panel'in one zone of the jacks and lamps 3 different positions in'the one zone of the switchboard. The conductor SW is the common starting wire and is connected to ,a contact on each of the line relays LR of with thefinder switch F S. The magnet RM is the rotary magnet of the finder switch F S and moves the wipers 2, 3, 4 and 5-over the bank contacts of the finder switch. The.

magnet- HM is aholding magnet for retaining the wipers of th finder switch in a selected position. The relay SCR is a sleeve cut-ofi' relay used for connecting the A talking conductors and. thefinder switch wipers 4. and 5 to the multiple jacks -MJ.

' The relay8 extends the starting conductor S'VV througli to the next finder switch FS (not shown) when the switch FS is taken for use. The finder switch FS also'includes a. double-wound slow-acting relay 9 and a single-wound quick-acting relay 10.

The cord circuit E comprises an answering plug P and a calling plug P; thecondensers 11 and '12 being interposed between the heavily marked conductors connecting the plugs P and P. Associated with the answering end of the cord circuit is an answering sleeve relay AS and an answering supervisory relay AT for controlling the circuit of answering .supervisory lamp AL. Relay AS also acts as-a test relay for controllingthe connection of the operator's telephone set OT to the strands of the cord circuit. l/Ve also provide a link disconnect relay LD to make possible instantaneous disconnection and recall. Associated with the calling end of the cord circuit E we provide a calling supervisory relay CT and a calling sleeve relay CS for controlling the circuit of the calling lamp CL. The calling sleeve relay CS also controls the disconnection of the operators set OT from the strands of the cord circuit. A party line ring key RK is provided for connecting one of a plurality of generators to the common ringing conductor CRL and for controlling the ringing control relay RC. The ringing control relay RC controls the ringing interrupter relay RI, which through the medium of the interrupter I applies ringing cunren't from the common conductor CRL to the line of the called subscriber, Associated with the cord circuit is a service register device comprising a meter magnet MM and a meter control relay MR. Associated with theoperators set OT is a revertive tone relay RTR.

a called substation C similar to the calling substation A and terminating in line equipment M similar to lineequipment M including a line relay LR, cut-ofi' relay CO, multiple jacks J and multiple finder switch bank contacts. 1

Having described in general the apparatus shown on the accompanying sheets of drawings, we will now describe indetailthe manner in which a call may be extended from the calling substation A to the called substation C. Assuming that the subscriber at substation A wishes to initiate a call, upon the removal of the receiver thereatla circuit is closed through the line relay LR including the two sides of the subscribers line circuit sinseries and the subscribers instrument.

from battery through the magnet RM of that the subscribers line relay LR was energized, off-normal contacts 15 and 16 would have been separated and the starting wire circuit would have been extended through alternate contact 19 of relay 8, through starting conductor SW and to the rotary -magnet RM of an idle finder switch. The

starting conductor SW is adapted to be extended through each busy switch in the series-of switches to the first idle switch in the series. The rotary magnet RM, upon energizing, starts to move the wipers 2, 3, 4 and 5 over the bank contacts of the finder switch in search of the calling subscribers line. When the-ofi-normal contacts ON are operated by the rotary magnet BM,

a substitute circuit is closed for magnet RM.

over a circuit extending -from battery through said magnet RM, off-normal contacts 15 and 20, contact 21 of relay 10, contact 22 of relay 9 and contact 23 of relay SCR to ground, thereby making the movement of the switch wipers of the finder switch FS independent of the starting circuit so that no matter if the calling subscriber should immediately replace his receiver, the finder switch FS will operate to move the wipers 2, 3, 4 and 5 over its bank contacts to the last contact thereof, unless a ounded contact is engaged.

s soon as the finder switch wiper 2 engages the grounded contact corresponding to the calling subscribers line, which contact was grounded through contacts 1.8 and 25 of line relay LR, the holding magnet HM and the relay 10 are energized in multiple over a circuit extending from ground through contacts 18 and 25 of line relay LR, bank. contact Q, wiper 2, normal contacts 26 of relay 8 to point 27 where the current divides and part flows through holding magnet to battery, and part through relay 10and lamps S to battery. Magnet HM upon energizing stops the wipers in engagement with the bank contacts of the calling subscribers line and holds the wipers in their advanced position. Relay 10- upon energizing opens the operating circuit of rotary magnet RM at its contact 21, and the magnet HM retains the wipers in their ad vancod position. A further result due to the energization of relay 10 is the closing of a circuit extending from battery through the winding of line relay 8, alternate contact 29 of relaylO, normal contact 30 of relay SCR, wiper 5 and its engaged bank contact, out through the calling substation and back through wiper 4 and its engaged bank contact, contact 31 of relay SCR, and contact 32 of relay 10 to ground. Relay 8 is thus energized over the calling subscribers line circuit. A still further result due to the energization of relay 10 is the closing of a circuit for cut-ofi relay C0 of the subscribers line circuit M, extending from battery through alternate contact 33 of relay 10, wiper 3 and its engaged bank contact and the cut-off relay CO to ground. Abusy potential is applied to the sleeve of the multi-n ple jacks J over this circuit. Relay 10 upon energizing also closes a circuit for relay 9 extending from battery through the lower winding of said relay 9' and through alternate contact 35 of relay 10 to ground. Relay 8 upon energizing extends the starting wire through its alternate contact 19 to the next finder switch and closes a substitute circuit for the holding magnet HM and for the relay 10 and multiple line lamps S. The

circuit for the multiple line lamps S extends from battery thru the said lamps S at their different operators positions, normal contact 36 of relay SCR and through alternate make-before-break contacts 26 of relay 8 to ground. Relay 8 is now entirely dependent upon-the circuit through the subscribers instrument for its flow of current, and the relay 10 and magnet HM are dependent upon the relay 8 for their holding circuits.

The cut-ofi relay 00 upon energizing disconnected the line relay LR from the subsoribers line and permitted the same to deenergize.v Had a second subscriber removedhis' receiver at the same time that the first subscriber removed his, or before the finder switch FS connected to the calling subscribers line and de-energized the subscribers line relay LR, the instant that the relay 8 of the finder switch FS was energized, the starting circuit would be extended through to the next finder switch and it would start in operation to find the other calling subscriber-7s line that was not picked up by the. first finder switch. As long as line relays LR are energized, finder switches FS will be started in search of calling subscribers lines. Of course, the

calling subscribe'rs line contacts appearing on the finder switch bank nearest to the normal position of the finder switch wipers will be the first to be selected. Likewise. if a finder switch should be restoring at the time that a call is being made, and the wipers of the finder switch restoring should contact with the contacts of the calling subscribers line before the finder switch that has been started from a normal position in search of the calling subscribers line'engages the calling subscribers line, then .the finder switch that is restoring will connect to the calling subscribers line and cause its multiple line lamps to be lighted and the finder switch started from its normal position, if it does not engage the contacts of a calling subscribers line before it reaches its fully operated switches does not find a grounded bank con-.

tact Q, then this finder switch will advance to its fully operated position, in which position a circuit will be closed through holding magnet HM and relay 10 in multiple and through normal contact 26 of relay 8, wiper 2, thelast bank contact Q, conductor 100, contact 22 of relay 9 and contact 23 ofrelay SCR to ground. As soon as this circuit is closed, magnet HM and relay 10 immediately energize. The energization of relay 10 and magnet however, is only momentary, but long enough to close a circuit for relay 9 extending from battery through the lower winding of said relay 9 and through alternate contact 35 of relay 10 to ground. Relay 9 upon energizing opens the circuit of rotary magnet RM, at

its contact 22 and closes a substitute circuit for magnet RM, extending from bat tery, through magnet RM, off-normal contacts 15 and 20, normal contact 21 of relay 10, alternate contact 22 of relay 9. through its upper high resistance winding, and through normal contact 23 of relay SCR to ground. The winding of relay 9 is of such a resistance as to remain energized in series with magnet RM, but to cause magnet RM to de-energize. The energization of relay 9 opened the energizing circuit for magnet HM and relay 10 at its contact 22, permitting relay 10 to de-energize and to close the above-mentioned locking circuit through the upper winding 'of-relay 9 before it had time to de-energize. Relay 9 is a slow-acting relay. Magnet RM becoming de-energized permits the wipers 2, 3, 4 and 5 to return to normal position and upon reaching normal position the off-normal contacts are restored to their normal positions, thereby opening the locking circuit for relay 9 and placing the apparatus in its normal position.

Returning now to the point where the finder switch had operated to select the calling substation A, and multiple line lamps S had been lighted at the different operators positions. an idle operator noting the glowing of calling line lamps S inserts the plug P of the cord circuit E into one of the multiple jacks MJ. The insertion of the cord circuit plug P into the jack MJ closes an energizing circuit for relay AS of the cord circuit and relay SCR of the finder switch, extending from'batter-y through the lower winding and through the upper test winding of relay AS in series,

normal contact 101 of relay LD, the sleeve contact of plug P and of jack MJ and through the winding of I relay SCR to ground. The relay AS energizing, providing that the cord circuit E is the first cord circuit to be connected to the jack MJ of the finder switch FS, closes a shunt about its upper high resistance winding at its contact 102, thereby placing its lower resistance winding in series with the relay SCR of the finder switch FS. This low resistance path extends through the lower winding of the relay AS to the sleeve of multiple jacks MJ and prevents the relay AS of other cord circuits from operatively energizing and connecting their associated operators sets to the line circuit of the calling subscribers line.

The relay SCR, upon energizing, connects the talking strands of the finder switch through to the tip and ring contacts of the jacks MJ at contacts 31 and 30 of said relay SCR, opens the circuit for multiple lamps S at-its contact 36, opens the circuit for relay 8 at its contact 30 but closes a substitute circuit for said relay 8 at. its alternate contact 103 before said relay'8 has had time to de-energize, and closes a substitute circuit for relay 9 at its alternate contact 23 before relay 9 has had timeto (lo-energize. The substitute circuit for relay 8 extends from battery through the winding thereof, alternate contact 29 of relay 10 and through alternate contact 103 of relay SCH to ground, and the substitute circuit for relay 9 extends from battery through the lower winding thereof and through alternate contact 23 to ground. Returning now to the cord circuit E, a further result due to the energization of combined test and supervisory relay AS is the bridging of answering tip supervisory relay AT across the subscribers talking circuit. The relay AT is immediately energized over the subscribers line to prevent a premature operation of the supervisory lamp AL and disconnect relay-Ll) by opening its normal contact 105, and closes its contact 106 to operate the meter relay MR and meter magnet MM. A still further result. due to the energization of relay AS is the bridging of the operators telephone, set OT across the strands of the cord circuit by closing its alternate contacts 100 and 107. The operators set is now connected across the strands of the cord circuit through alternate contacts 106 and 107 of relay AS and normal contacts 108 and 109 of relay CS. The operator now being in connection with the calling subscriber inquires tlie wants of the calling subscriber.

Assuming that it is a subscriber at. the substation C that is wanted. the operator tests the line of the called subscri er and if it is idle, she. then inserts the calling plug P into a jack J connected to the line circuit of the called subscriber. If the line of the called subscriber is busy, the touching of the tip of the plug P to the sleeve of a jack J will closea circuit from the busy or battery potential upon the jack J, through the tip of the plug, through contact 109 of relay RI, through contact 110 of relays CS and through the tertiary winding of the operators induction coil to condenser 200 and to ground, thus giving the operator a busy click in her receiver, notifying her of the busy condition of the called line. The operator thereupon notifies the calling subscriber that the called subscribers line is busy.

Assuming that the called subscriber is a subscriber whose substation is connected to the line of the calling subscriber, the touching of a multiple jack of the calling subscribers line by the plug P closes a circuit from the battery or busy potential found upon the sleeve of multiple jack J,

- through the tip of plug P, through contact 109 of relay RI, through contact 110 of relay CS and through revertive tone relay R-TR to ground. Relay RTR upon energizing closes a circuit from the tone device TD through alternate contact 111 of relay RTR, through contact 112 of relay AS, through normal contact 113 of relay CS,through normal contact 101 of relay LD to the sleeve of a multiple ack MJ, from the sleeve of multiple jack MJ, through the condenser 117, through alternate contact 33 of relay 10, wiper 3 and engaged contact P to a multiple jack J thence through the jack J which is being engaged by the tip of plug P, through the tip of said plug and contact 109 of relay RI, through contact 110 of relay CS, through the tertiary winding of the operators induction coil, and through the condenser 200 to ground, thereby giving the operator a revertive tone test. The operator then plugs into the jack of the subscribers line and completes the connection in a manner to be hereinafter described.

Assuming that the called subscribers line is idle, the insrtion of the calling plug P into the jack J of the called subscribers line closes an energizing circuit for the calling sleeve supervisory relay CS and the cut-off relay CO over a path extending from battery through the winding of said relay CS, the sleeve contacts of the plug P and jack J. and the winding of relay CO to ground. Relay CO upon energizing disconnects the line relay LR from the line circuit of the called subscriber. The calling sleeve relay C S upon energizing disconnects the operators set OT from the strands of the cord circuit at its contacts 108 and 109, opens the circuit of revertive test relay RTR at its contact 113, and closes 'a circuit through the calling supervisory lamp CL at its alternate vof relay CS to ground.

contact125. The circuit for the lamp CL may be traced from battery through the said lamp, normal contact 126 of relay RC, normal contact 127 of relay LD, normal contact 128 of relay CT and alternate contact 125 to ground. A further result due to the energization of relay CS is the opening of the circuit for meter relay MR at normal contact 125 of relay CS. The relay MR deenergizing opens the circuit of nrter magnet MM, thereby permitting the same to de energize. I

The calling lamp CL is the customary calling supervisory lamp forindicating to the operator whether or not the'called subscriber at C has his receiver upon the switch hook. The operator next depresses one of the ringing key plungers to connect one of the ringing generators to the common ringing conductor CRL and to initiate the operation of the automatic ringing equipment;

The operation of end spring 130 of the ringing key closes a circuit for interrupter relay RI extending from battery through the upper winding of said relay, closed contact 130 of the end springs, normal contact 127 of relay Ll normal contact 128 of relay CT and alternate contact 125 of relay CS to ground. Relay RI upon energizing disconnects the strands of the cord circuit from the ring and tip conductors of plug P and connects the selected generator through alternate contact 109 of said relay IR to the called subscribers line, through the call bell at the called substation and back through alternate contact 132 to ground, thus insuring a preliminary ring of the call bell at the called substation the instant that ring key RK is operated. A further result due to the energization of relay RI is the connection of an audible ringing tone to the calling subscribers line through alternate contact 133 of said relay RI to indicateto the calling subscriber that the call bell at the called substation is being operated. A still further result due to the energization of relay RI is the closure of an energizing circuit for ring control relay RC extending from battery, through the winding of said relay RC, alternate contact 134 of relay RI, normal contact 127 of relay LD, normal contact 128 of relay CT and alternate contact 125 of relay CS to ground. The relay RC upon energizing clos's a locking circuit for itself extending from battery through its winding, its alternate contact 126, normal contact 127 of relay LD. normal contact 128 of relay CT and alternate contact 125 A still further result due to the energization of relay RC is the opening of the circuit of calling supervisory lamp CL at normal contact 126 and the closing of a circuit for interrupter relay RI, extending from battery, through the lower winding of relay RI and through circuit and relay SCH of the finder switch incense alternate contact 135 of relay R0 to interrupter l. The ringing relay BI is thus intermittently energized to connect ringing current to the called subscribers line to operate the call bell thereat.

Upon the response of the called subscriber, a circuit is closed through the calling tip supervisory relay GT, extending from battery through the lower winding of said relay, through contact 132 of relay RI, through the ring contacts of the plug 1? and jack J out over the called line, back through the tip contacts of the jack J and the plug P, through contact 109 of relay. RI, through alternate contact 110 of relay OS and through the upper winding of relay CT to ground. Relay GT upon energizing opens the locking circuit of relay RC at its contact 128, thereby preventing further application ofringing current to the called subscribers line. The relay RC de-energizing closes the link strands through to the called subscriber and disconnects the interrupter I from the interrupter relay RI. The subscribers may now carry on conversation over the heavily marked conductors.

Assuming now that conversation is finished, the subscriber at substation A upon replacing his receiver upon the switch hook opens the energizing circuit of answering tip relay AT. Relay AT upon tie-energizing.

closes an energizing circuit for the link disconnect relay LD at its contact 105." The circuit for link disconnect Ll) extends from battery, through its winding, through said contact 105 of relay AT, through alternate contact 137- of relay AS and through alternate contact 125 of relay CS to ground. Relay Ll) upon energizing opens the series energizing circuit for relay AS of the cord at its normal contact 101 and closes a substitute circuit for relay AS extending from battery-through the lower winding of said relay AS, alternate contact 102 of said relay.

AS, alternate contact 101 of relay Ll), alternate contact 137 of relay AS and alternate contact 125 of relay GS to ground. A further result due to the energization of relay L1) is the disconnection of the tip and ring conductors of the cord circuit E and the tip and ring conductors of jacks MJ, thereby operatively disassociating the calling subscribers line and the finder switch F8 from the link. circuit E.

The relay SCR of the finder switch FS de-energizing opens the energizing circuit of relay 8, which relay upon tie-energizing opens the holding circuit for holding magnet HM and -for relay 10. The holding magnet HM and the relays 8, 9 and 10 deenergizing permit the wipers 2, 3, 4 and 5 of the finder switch ES to return to normal.

. The finder switch FS may now be used by another calling subscriber or by the same calling subscriber in extending a call to the multiple jacks MJ and line lamps S even though the plug P be left in connection'with the multiple jacks Mil. It will be seen by this arrangement that we greatly decrease the length of time that the finder switch FS would be held in use if it was GS to ground. The operator upon noting the glowing of the answering supervisory lamp AL and the calling su ervisory lamp CL removes the answering p ug P from the jack MJ and'the calling plug P from the jack J. The removal of the calling plug P from the jack J allows the cut-ofi' relay G0 and calling sleeve relay C8 to de-energize. The relay GS upon ole-energizing opens its alternate contact 125, thereby opening the locking circuit for the link disconnect relay LD, answering sleeve relay AS and for the supervisory lampsCL and AL.

Relay Ll) and the relay AS upon de-ener- .gizing restore the cord circuit apparatus to normal rendering it available for connecting other subscribers lines.

Should the calling subscriber desire to recall before plug P is removed from the jack MJ, he may do so. The subscriber upon removing his receiver for a recall again energizes line relay LR, thereby grounding the common start wire SW and starting another finder switch FS or the same finder switch in search of the calling subscribers line. As soon as the finder switch finds the calling subscribers line, the connection is completed the same as heretofore described. If the same finder switch is started that was used in the previous connection, the finder switch upon finding the calling subscriber s line will again cause the lamps S to glow and either the same operator or another operator may seize the recall.

If the wipers or the finder switch FS should be restoring to normal and a grounded contact Q, be' engaged by wiper 2 of the finder switch, a circuit will immediately be closed through the holding magnet HM andthe relay 10 in parallel, which circuit extends through contact 26 of relay 8 and test wiper 2 to the ounded bank contact Q. The magnet H upon energizing, of course, stops the retrograde movement of the wipers and holds them in engagement with-the contacts of the calling line. Relay 10 u on energizing closes circuits for relay 8. an relay 9. as before described, and causes the multiple lamps S to glow. This call will be attended to by an idle operator in the regular manner and the connection completed as before described. The calling sub scriber when he replaces his receiver, as before mentioned, causes the link disconnect relay LD otthe cord circuit Etc be energized, operatively disassociating the cord circuit C from the multiple jacks MJ, thereby freeing the finder switch F8 for further use. The finder switch FS restoring opens the circuit of the cut-oil relay C0 of the callin subscriloers line.

In escribing our invention we have shown a certain form of finder switch and a specific feature of cord circuit, but it is to be understood that various types of finder switches and various types of cord circuits maybe used with our invention.

In working out our invention we have employed preferred circuit arrangements all of which tend to make an eficient operating system, but it is to be understood that various chan es and modifications may readily be made without parting from the spirit and scope of our invention. Therefore, we do nection circuit, and subscriber-controlledmeans individual to said link circuit for operatively disassociating said link circuit from said connection circuit whereby said calling subscribers line is disconnected from said connection circuit,

2. A telephone system including subscribers telephone lines, a manual switchboard, link circuits, multiple jacks and multiple lamps in which said link circuits terminate, said multiple jacks 'and multiple lamps appearing before a plurality of operators at said manual switchboard,

automatic means for connecting one of said link circuits to one of said calling sub scribers lines and for causing the multiple lamps associated with said link circuits to glow, operators cord circuits for connecting to said link circuits, and subscriber-controlled means for automatically disassociating one of said cord circuits from one of said link circuits.

3. A telephone system including subscribers telephone lines, link circuits terminating in multiple jacks and multiple lamps before a plurality of operators at a manual board, automatic means for connecting one of said link circuits to one of said calling subscribers lines and for causing the multiple lamps associated with said link circuit to glow, operator-controlled cord circuits, any one of which may be used for extending the connection from said link circuit to a called subscrihers line, and subscriber-controlled means individual to each of said cord circuits for automatically disassociating said cord circuit from said link circuit.

4. A telephone system including subscribers telephone lines, link circuits terminatingin multiple jacks before a plurality of operators at a manual board, multiple line lamps associated with said jacks, automatic means for connecting one of said link circuits to one of said calling subscribers lines and for causing the multiple lamps associated with said link circuitto glow, cord circuits, any one of which may be used for extending the connection from said link circuit to a called subscribers line, and means individual to each of said cord circuits for preventing the operative association of more than one of said cord circuits with said link circuit.

5. A telephone system including a plural- ,ity of subscribers telephone lines, a link circuit common to said telephone lines and terminating in a plurality of multiple jacks, multiple line lamps associated with said jacks, a plurality of operators positions at which said jacks and lamps appear, automatic meansfor connectingsaid link circuit and a calling one of said subscribers lines and for causing the multiple lamps associated with the link circuit to glow, an operators cord circuit for extending the connection from said link circuit, and subscriber-controlled means for automatically disassociating said cord circuit from said link circuit whereby said calling subscribers line is disconnected from said link circuit.

6. A telephone system including a plurality of subscribers telephone lines, a link circuit common to said telephone lines, a plurality of multiple jacks in which said link circuit terminates, multiple line lamps associated with said jacks, a pluralityot operators positions at which said jacks and lamps appear, automatic means for connecting said link circuit and a calling one of said subscribers lines, an operators cord circuit for extending the connection from said link circuit, and subscriber-conaseaoae cord circuit from said link circuit.

7. A telephone s stem includinga manual switchboard rovi ed with. answering jacks and with m tiplej acks for calling purposes, and means including an automatic rotary switch for increasing the number of lines appearing upon said board by decreasing the number of answering jacks appearing noon the same and increasing the number oi multiple jacks appearing upon the same,

--;said automatic switch operable when a call is initiated to pick out and make connection with the line on which said call isinitiated.

8. A telephone system including a manual switchboard, subscribers answering jacks and multiple jacks entirely filling the space in the face of said switchboard, means including automatic rotary switches for increasing the number of lines appearing upon said switchboard by arranging the answering jacks lILgTOIlPS common togroups of subscriberslines, thereby decreasing the number of answering jacks and permitting an increase in the number of multiple jacks, said automatic switches being associated with. said groups of subscribers lines and operable when calls are initiated to pick out and make connection with the lines on which said calls are initiated to extend said lines to the answerin jacks associated with said automatic switc es.

9, A telephone system including a manual switchboard provided with multiple answero jacks,

10, A telephone system including a manual switchboard having multiple answering jacks and lamps for subscribers lines for answering purposes, multiple jacks for said subscribers lines for calling purposes, and means including automatic switches for decreasing the number of answering jacks and permitting the number of calling jacks to be increased, said switches operable in a progressive or retrograde direction to select said lines as calling lines and to associate the same with said multiple answering jacks and lamps.

11. A. telephone system including a manual switchboard provided with multiple answering jacks and lamps common to subscribers" lines, automatic means including automatic switches operable in .a progressive or retrograde direction for connecting said subscribers lines and said answering V jacks, multiple jacks through which said subscribers lines may be called as called,

lines, and means for decreasing the number of answering jacks and permitting an increase in the number of multiple jacks.

12. A telephone system includin a group of subscribers lines, a'group of circuits -for said subscribers lines, multiple answering jacks and lamps upon a manual switchboard in which said link circuits terminate, and automatic means controlled by the subscribers for interconnecting said link circuits and subscribers lines and for causing the said multiple lamps to glow, operators cord circuits common to said subscribers lines, and means in said cord circuits for preventing the operative association of more than one of said cord circuits with onset said link circuits at the same time.

13. A telephone system includin a group of subscribers lines, a group of ii circuits for said subscribers lines terminating in multiple answering jacks and lamps upon a manual switchboard, automatic means controlled by the subscribers for interconnecting said link circuits and subscribers lines and for causing the said multiple lamps to glow, operators cord circuits, and means in said cord circuits for preventing the operative association at the same time of two of isaid cord circuits with a calling subscribers 14. A telephone system including'a group of subscribers line circuits, link circuits common to said line circuits, automatic switches adapted to interconnect said link circuitsand said subscribers lines, said antomatic switches being provided with individual driving'mechanism andarranged to select during either a forward or a retrograde movement, and means for returning said switch to normal position.

, 15. A. telephone system including subscribers telephone lines, link circuits common to said lines, and automatic switches adapted to select upon either a forward or upon a retrograde movement, for interconnecting said subscribers lines and said link circuits, individual driving mechanism for advancing said automatic switches, and spring means for returning said automatic switches.

16. A. telephone system including subscribers telephone lines, link circuits, automatic progressively movable switches for interconnecting said link circuits and said subscribers telephone lines, cord circuits for extending connections from said link circuits to called subscribers lines, revertive test means for said cord circuits for testing a multiple contact of a calling subscribers line, and automatic disconnectmeans for said cord circuits for disassociating said tie &

board in which said link circuits terminate,

finder switches for connecting an idle one of said link circuits to a calling one of said subscribers lines and for causing the multiple lamps associated with said link circuit to glow, a plurality of operators cord circuits situated at difi'erent operators positions adapted to extend a call from any of the multiple jacks associated with said link circuit towards the called subscribers line,

and subscriber-controlled means in said cord circuits for operatively disassociating the connected cord circuits from one of said multiple jacks.

18. A. telephone system including a plurality of subscribers telephone lines, link circuits common to said subscribers telephone lines, multiple jacks and multiple lamps upon a multiple line lamp switchboard in which said link circuits terminate, finder switches for connecting an idle one of said link circuits to a calling one of said subscribers lines and for causing the multiple lamps associated with said link circuit to glow, a pluralit of operators cord circuits situated at 'ifl'erent operators positions adapted to extend a call from any of the multiple jacks associated with said link circuit towards the called subscribers line, and means individual to each of said cord circuits "for preventing the operative association of more than one of said cord circuits with said link circuit at the same time.

19. A telephone system including a plurality of subscribers telephone lines, link circuits common to said subscribers telephone lines, multiple jacks and multiple lamps upon a multiple line lamp switchboard in which said link circuits terminate, finder switches for connecting an idle one 01 said link circuits to a calling one of said subscribers lines and for causing the multi ple lamps associated with said link circuit to glow, a plurality of operators cord circuits situated at diiferent operators posi tions adapted to extend a call from any of the multiple jacks associated with said link circuit towards the called subscribers line, means individual to eachof said cord circuits for preventing the operative association of more than one of said cord circuits with said link circuit at the same time, and multiple jacks for said subscribers lines incense whereby the said cord circuits may-be used to extend connections to the subscribers lines as called subscribers lines.

20. A telephone system including calling subscribers lines, multiple answering jacks for said subscribers lines located upon a manual switchboard at difierent positions thereof, automatic'progressively and backwardly movable means for interconnecting said jacks and said telephone lines, op-

erators cord circuits for extending connections from said answering jacks to multiple jacks of called subscribers lines, and spring means for returning said automatic means to normal.

21. A telephone system including sub-' scribers telephone lines, a manual switchboard, answering ja'cks for said subscribers lines less in number than said lines, said answering jacks being multipled and appeering in a plurality of positions in said manual switchboard, subscriber-controlled means for interconnecting said subscribers lines and said answering jacks, and operators cord circuits for extending connections from said answering jacks to called subscribers lines, said cord circuits being provided with callin subscriber controlled means for operative y disassociating said cord circuits from said answering jacks.

22. A telephone system including a group of calling subscribers lines, a manual switchboard, answering jacks for said subscribers lines less in number than said subscribers lines, said answering jacks being multipled at a plurality of positions on said manual switchboard, individual multiple jacks for said subscribers lines appearing upon said switchboard, subscriber-controlled means for interconnecting said answering jacks with said subscribers lines, cord circuits for answering calls from said subscribers lines and for extending calls to said subscribers lines through the multiple jacks thereof, and test means individual to each of said cord circuitsfor preventing the operative association of more than one of said cord circuits with one of said calling subscribers lines at the same time.

7 23. A telephone system comprising a number of telephone lines, a number of signals arranged in groups, the signals of a group distributed to various operators and the number of groups less than the number of lines and common to them, automatic selecting and connecting switch mechanism respons1ve to line controlled currents to temporarily individualize to a line a group of said signals and display them before the various operators, and switching apparatus to enable any operator of a plurality to operatively connect her position with the line causing the display of her signal and to prevent other operators whose nuances signals are displayed from operatively connecting to said line causing the display of said other operators signal.

24:. A telephone system including lines and a pair thereof in conversational relation with each other, an operator controlled plug and spring jack contact in the talking circuit, a link circuit having a signal for indieating a call at the position of said operator, said circuit included in the connection between said operato'rsposition and said calling line and normally available to any of a plurality of lines, selecting and connecting mechanism between said link circuit and said lines for automatically individualizing said link circuit to any calling line, and now individualizing saidcircuit to the calling line of said pair, and substation controlled means operated over a circuit including a portion of the talking circuit between said connected lines for automatically and without the aid of the op erator rendering said link circuit and its signal available for individualization to another line of said plurality.

25. A telephone system including telephone lines, and a less number of link circuits, selooting and connecting mechanism between said link circuits and lines for automatically connected idle link circuits with calling lines, operators positions and plug and jack connections thereat for extending the connections of said link circuits, and means controlled over a calling line for automatically causing a link circuit connected thereto to become idle while the plug and jack connection extending the connections of said link circuit remains complete.

26. A telephone system including telephone lines, a pair thereof connected for conversation, a link circuit having a. plug connector at one end and automatic selecting and connecting switch mechanism at the other and normally available for interchangeably associating said link circuit with various lines, said link circuit being included in the connection between said pair of lines, and means controlled over one of said connected lines independently of the operator for automatically dividing said link circuit and rendering the end toward said switch mechanism available for association with other lines.

27. A telephone system including tele phone lines and a less number of groups of signals, the signals of each group distributedamong various positions of the switchboard, automatic mechanism enabling any calling line to individualize to itself oneof said groups and display the signals thereof and apparatus enabling any of the operators at whose positions the signals are displayed to individualize the call to her position, and release means actuated over a connected line independently of the operator to render the plug and jack contacts extending the circuits of lines, and disconnect apparatus op--= erable over a line to restore an individualized group of line signalssoas to be common to said lines while the plug and jack contact extending said line is intact.

29. A telephone system including a group of telephone lines and a switchboard having multiple jacks for outgoing, calls and an swering jacks for incoming calls, the an swering jacks arranged in groups and the jacks of a group located before difierent operators and each answering jack havin an associated call indicating signal, a ca ling line and apparatus operable responsive to current thereover to individualize to itself any idle group of answering jacks and dis play the signals of such groups, a cord circuit having an answering plug for connecting to an answering jack connected to the calling line and a calling plug for connect ing to a multiple jack for extending the call toward the called line, and disconnect apparatus operable responsive to current changes produced in said calling line to de-individualize the associated group of answering jacks and render said group common to said group of lines while the answering and calling plugs are in said jacks.

30. In combination with the calling telephone line, a plurality of multiple connecting terminals located at a central ofice switchboard, an automatic switch for selecting said calling line and for extending the same to said multiple connecting terminals, a cut-ofi relay for said switch having its coil connected to one of said multiple terminals, operators link circuits distributed among operators positions of said switchboard and means initially operated through a circuit including the coil of said cut-0d relay where by any one of said link circuits may be con nected to any one or" said multiple terminals when answering a call to the exclusion of the remaining link circuits that attempt to answer the call.

31. A telephone call distributing system. comprising a plurality of subscribers telephone lines, a central oilice switchboard, a plurality of answering terminals and asso ciated calling signals, said lines distributed among operators positions at said switchboard, an automatic switch for selecting said lines as calling lines and for extending the i switch, a plurality of connecting terminals and associated line signals, the connecting terminals and associated signals being distributed among operators ositions of the switchboard, means control ed at the substation of said lines for causing the operation of said switch to extend the line of said substation to said terminals and to cause the operation of said associatedsignals to extend a call to a number of said operators positions, link circuits at each of said positions for extending the calls, and means included in said link circuit and initially operated through the coil of the cut-ofi relay of said switch whereby when. one of the link circuits is connected to a calling terminal, a second one of said link circuits cannotbe operatively connected to another terminal ofthe same calling line.

33. A telephone system including telephone lines, a central oilice switchboard, a line relay for each line,-an automatic switch, a cut-ofi relay for said switch, a plurality of connecting terminals and associated line signals common to said lines, the connecting terminalsand associated signals being distributed among operators positions of said switchboard, means controlled at a substation of said lines for operating said line relay whereby said switch operates to extend the line of said substation to said terminals and to operate the associated signals to extend a call to a. number of said operators positions, link circuits at each of said positions having answering. terminals adapted for connection with said connepting terminals, and means initially operated through I the coil of said cut-ofi' relay whereby when one of said answering terminals isconnected to a connecting terminal to which a calling line is extended, a second one of said link circuits cannot be operatively connected by its answering terminal to another connecting terminal in circuit with the same calling line.-

34'; A telephone system including telephone lines each having a line relay, a plurality of connecting terminals, an automatic switch n u -0n to said telephone lines and adapted to select any one of said lines when one answering terminal with the connecting terminals to which one of said lines has been extended.

35. A telephone system including telephone lines, an automatic switch, a cut-oil relay ,for said switch, 'a pluralit of connecting terminals common to said ines but less in number than said lines, said switch adapted to extend any one of said lines as a call-- ing line to said connecting terminals, link circuits having manually operated answering terminals adapted for connection with said connecting terminals, and means to initially operate throu h the coil of the cutoff relay when one c said answering ter- -minals is connected to a connecting terminal having a calling line extended thereto to prevent the operative association of a second link circuit when the answering terminal of such second link circuit is connected to another connectin terminal to whichthe same line'has also been extended.

36. A telephone systemcomprisin telephone lines each terminating in oan contacts of a plurality of automatic switches, multiple jacks distributed among a plurality of positions on a central ofice switchboard, said switches operable to select said lines as calling lines and to extend the same to said multiple jacks, operators manual link circuits at each of such position for conv necting to said multiple jacks in answering calls, and test means included in said link circuits automatically operable upon connection of a link circuit with a terminal having a calling line extended thereto in answering a call for determining its answered or unanswered condition, and supervisory means for said link circuits operable when disconnection is signalled for.

37. A two-conductor telephone system comprising a telephone line, an automatic switch, said line terminating in the bank contacts of said switch, multiple jacks at 'a central office switchboard, said switch operable to extend said telephone line tosaid multiple jacks, a line signal for eachof said multiple jacks, link circuits for connection to said multiple jacks, means whereby, when i a link circuit is connected to one of said multiple jacks when said line has been extended to said jacks, and the substation on said line is operated for disconnection, the

conductors of the link circuit are disconnected from said multiple jacks and said line and switch are available for use in operating said signal for calling before or nccaa after said link circuit is disconnected from said multiple jacks, and means ,for permitting a second link circuit to be operatively connected to any one of said multiple jacks to extend a second call before said first link circuit has been restored .to normal and for .nected and distributed among operators positions of said switchboard, an automatic switch for selecting said lines as calling lines and for extending the same to said answering jacks, link circuits having terminals which may be simultaneously and continuously connectedto the multiple jacks to which the same line hasbeen extended and so arranged that only one operator at a time may operatively connect to one of said answering jacks to. answer a call thereat and extend connection to a jack of another line as a calling jack, an automatic disconnecting means for said link circuits for 'disassociating a connected link circuit and an automatic switch and a telephone line when the subscriber of said line retires, whereby said switch and telephone line are available for calling or called purposes.

39. In a telephone system including a calling two-conductor telephone line, a nonnumerical automatic switch, a connecting jack at a central oiiice switchboard, said switch operable to operatively associate said calling telephone line with said connecting jack, a called telephone line and operators link circuit having a manual answering terminal normally connected with the conductors of the link circuit for connecting to said connecting jack, a calling terminal for said link circuit for connecting to said called telephone line, and means under thesole control of the substation on said calling line for operatively disassociating said link'circuit from said automatic switch and calling line after the conversational circuit between calling and called lines has been completed 40.1n combination with the calling telephone line a plurality of connecting terminals'for said line located at operators positions of a central ofiice switchboard, an automatic switch for operatively associating said telephone line with said connecting terminals, operators link circuits having associated operators telephones, said link circuits including -means eflective whereby, when one of said link circuits and asso- .ciated operators telephone is connected to one of said terminals, a second link circuit which is physically connected to another terminal operatively associated with said line cannot be operatively connected to another operators telephone, and automatic means for rendering the connection of said first link circuit inefi'ective and to permit the connection of said second link circuit to be operatively efiective to connect'another operators tele hone.

41. A combination with a two-conductor calling telephone line, a connecting jack, -a non-numerical automatic switch for extending said calling telephone line to said connecting jack, a link circuit at the exchange for connecting to said jack and to a called telephone line, means under the-sole control of the substation of said calling line to disassociate the calling line and automatic switch from said link circuit and to render-the calling line and automatic switch available for recall when signalling for disconnection at all times prior to the time when the called subscriber signals for disconnection.

42. A call distributing system comprising telephone lines, a plurality of jacks at the central exchange, signals for said jacks,

automatic switches common to said lines and jacks and operable to select said lines as one of said link circuits and thereby'to prevent the operatixge association of a second operators telephone with the remainder of sai link circuits.

43. In a telephone system, a telephone line, an automatic switch, a plug-ended link circuit, an operators telephone, means for connecting said linkcircuit to said line through the medium of said plug and automatic ewitch,'means under the control of the substation on said line for disconnecting said line from said plug, and means for reconnecting said line and switch and said link circuit prior to the withdrawal of the said plug and for connecting the operators telephone to the said telephone line.

44. In a telephone system, a telephone line, an automatic switch, a plug-ended link circuit, means for connecting said link circuit to said line through the medium of said plug and automatic switch. an operators telephone, means under the control of the substation on said line for disconnecting said line and automatic switch from said link circuit, and automatic means for 

